The present invention relates to a strut mount to be interposed between a shock absorber and a vehicular body in a vehicular suspension.
FIG. 5 is an essential-part magnifying sectional view of an automotive suspension including a conventional strut mount 100. As shown in the figure, the suspension is provided with a shock absorber 122 having an outer tube 120 to be connected to a wheel side and a piston rod 121 to be connected to a vehicle-body side. Also, a coiled spring 124 is coaxially arranged over an outer periphery of the outer tube 120 and shock absorber 121.
The strut mount 100 comprises an inner cylindrical metal member 101 to which a tip of a rod 121 of the shock absorber 122 is inserted, a rubber elastic member 102 adhered by vulcanization to an outer periphery of the inner cylindrical metal member 101 in a manner surrounding same, and an outer metal member 103 in a case form receiving the rubber elastic member 102. The rod 121 at its tip is inserted in the inner cylindrical metal member 101 and tightened with a nut 104, thereby fixing the tip of the rod 121 to the inner cylindrical metal member 101. Also, the outer metal member 103 is attached to the vehicular body 130 by bolts 105 and nuts 106. The inner cylindrical metal member 101 has, in an axial center, a flange-like projection 107 so that the rod 121 is regulated from displacing a predetermined amount or more in a vertical direction and a horizontal direction of the vehicle by the projection 107.
In the strut mount as above, there is generally a requirement and devising made to decrease the rigidity against the displacement of the rod 121 in a vertical direction of the vehicle and increase the rigidity against the displacement of the rod 121 in a left-and-right direction of the vehicle. Also, there are cases for a requirement to decrease the rigidity against the displacement in a wrench direction of the rod 121 (i.e. rod-inclining direction) besides the properties for such vertical direction and left-and-right direction. This because, if the rigidity in the wrench direction is high, the rod 121 has friction with a top end of the outer tube 120 thus giving a cause of vibration, and because of the need to increase the thickness of the rod 121 from the problem with strength.
However, in the conventional strut mount 100, it is structurally difficult to decrease the rigidity in the wrench direction without changing the rigidity in the vertical direction and left-and-right direction of the vehicle. Thus, the foregoing requirement cannot be met.
The present invention has been made in view of the above points, and it is an object to provide a strut mount capable of reducing the rigidity in a wrench direction of the rod.
A strut mount of the invention is a strut mount to be interposed between a shock absorber and a vehicular body in a vehicular suspension, comprising: an inner member having a fixing surface portion vertical to a rod of the shock absorber and an aperture provided in the fixing surface portion to which a tip of the rod is inserted from below; an outer member surrounding an outer periphery of the inner member and to be mounted to a vehicular body; and an elastic member uniting the inner member and the outer member together; wherein the elastic member unites the inner member and the outer member on a side above the fixing surface portion fixed with the rod; and a gap being secured circumferentially between the inner member and the outer member on a side below the fixing surface portion.
In this strut mount, the rod of the absorber is fixed on the fixing surface portion of the inner member vertical to the rod, and the elastic member unites the inner member and the outer member together only on a side above the fixing surface portion while a gap is circumferentially secured between the inner member and the outer member on a side below the fixing surface portion. Accordingly, rigidity can be reduced in a wrench direction of the rod. Also, by adjusting the size of this gap, the wrench angle of the rod usually less than 5 degrees in the conventional can be increased to 10 degrees or more, for example, to nearly 15 degrees. It is thus possible to cope with a vehicular model requiring an increased wrench angle.
In the strut mount of the invention, there may be a case that the inner member comprise a cup-like member having the fixing surface portion as a bottom and opened to the above, the outer member having an inner peripheral wall surrounding an outer periphery of the cup-like member, and the cup-like member at a side wall spreading in an inverted-taper form directed toward the above, to have an outer peripheral surface of the side wall united with the inner peripheral wall of the outer member by the elastic member. By slanting the side wall of the inner member upward and outward in a united portion of the inner member and outer member by the elastic member like this, the rigidity in the rod-wrench direction can be reduced further effectively.
In this case, the inner member may comprise a first member that is the cup-like member and a cup-like second member opened to the below to receive the tip of the rod from the below, to form the fixing surface portion by uniting together bottom surfaces of the first member and the second member, and the gap being secured over an outer periphery of a side wall of the second member.
In the strut mount of the invention, there may be a case that the gap be formed different in size in a circumferential direction. By circumferentially making different in this manner the size of the gap secured between the outer member and the inner member on a side below the fixing surface portion, the wrench angle of the rod can be varied in the circumferential direction. In this case, the gap at radially opposite two portions is preferably formed greater than in the other portions. For example, by increasing the gap at opposite two portions in a front-and-rear direction of the vehicle, the wrench angle in the front-and-rear direction can be given greater than the wrench angle in a left-and-right direction of the vehicle. The measure for making the gap circumferentially different in size in this manner involves that the outer member comprises an inner peripheral wall surrounding the outer periphery of the inner member, and a spacing between the inner peripheral wall of the outer member and the inner member being set different in size in a circumferential direction on a side below the fixing surface portion.
In the strut mount of the invention, also, the inner member comprises a cup-like member having the fixing surface portion as a bottom and opened to the above, the outer member having an inner peripheral wall surrounding an outer periphery of the cup-like member, an outer peripheral surface of a side wall of the cup-like member and the inner peripheral wall of the outer member being united by the elastic member, and the cup-like member at a top-end opening having a flange radially outwardly extending beyond the inner peripheral wall of the outer member, to have a cutout provided at least in a circumferential part of the flange. By doing so, the wrench angle of the rod can be varied in the circumferential direction. In this case, the cutout is preferably provided at radially opposite two portions. Also, by forming the gap in a position radially opposite to the cutout greater than in the other portions, the circumferential change of the wrench angle can be increased furthermore.